Annual herb with prostrate of climbing stems up to 10 m long, covered in long spreading hairs, particularly when young. Tendrils2-3-fid. Leaves more or less narrowly ovate in outline, up to 20 × 19 cm, usually deeply palmately 3-5 lobed with lobes elliptic in outline and often lobed again; hairy when young, particularly on the veins beneath, becoming roughly punctate when oleder; margins almost entire or obscurely and finely sinuate-dentate. Flowers solitary, axillary, yellow, unisexual on the same plant. Fruit smooth, in wild plants 1.5-20 cm long, greenish with darker mottling; cultivated fruits much larger and often more elongated ellipsoid, up to 60 × 30 cm.